Presentation of Aqueductal Stenosis in Children

Symptoms

Infants

Rapid head growth: In the first year of life the clinical presentation usually consists of a rapid increase in head circumference (87, 112).

Developmental delay: Congenital aqueductal stenosis is associated with moderate to severe developmental delay in high percentage of cases (73% in the series of Levitsky et al. (68)) despite optimal neonatal surgical treatment.

Children and adolescents

Headache: Headache is the most frequent symptom. It is exacerbated by coughing, sneezing, straining and stooping. The site is variable and the headache is usually described as occurring in attacks that may last for seconds or minutes or may continue for days. During attacks nausea, vomiting, drowsiness, a sensation of weakness in the legs and even falls may occur. Headache and drop attacks could be due to sudden changes in pressure relationship (69).

Epilepsy: Epilepsy is present in about 15% of cases (43), especially in temporal lobe and generalized seizures (69). It is related to the distress of the cerebral cortex due to increased ICP. Seizures may not regress with the treatment of hydrocephalus.

Visual disturbances: Visual disturbances are related to papilledema and chronic compression of the optic chiasm caused by an enlarged third ventricle. The most common complaints are reduction of visual acuity, visual field defects and unilateral or bilateral blurring of vision (15).

Ocular movement disorders: Ocular disorders, ranging from paresis of upward gaze to the complete syndrome of aqueduct of Sylvius are the most characteristic signs of aqueductal stenosis (15).

Global rostral midbrain dysfunction: This appears with progression of hydrocephalus and is characterized by signs of ventral midbrain involvement such as a parkinsonian-like state (tremor, bradykinesia, masked face and cogwheel rigidity), spastic quadriparesis and alteration of level of consciousness (1, 18). The ongoing involvement of the substantia nigra with its nigrostriatal and nigrocortical connections, the cerebral peduncles and the midbrain’s reticular formation explains all these symptoms.

Endocrine abnormalities: Endocrine manifestations occur in 10% of adolescents and adults with aqueductal stenosis (43, 89). The chronic compression of the hypothalamo-hypophyseal axis by an enlarged anterior third ventricle, may explain both hypophyseal hypofunction and hyperfunction. Dyencephalo-hypophyseal compression can reduce secretion of hypophyseal hormones, and of hypothalamic inhibitor hormones resulting in increased hypohyseal function. Endocrine findings may vary between males and females (89). In male the most frequent findings are obesity, hypogonadism (with impotence and infertility) diabetes insipidus, precocious puberty and, more rarely, lethargy, gigantism and acromegaly. In females the most frequent findings are amenorrhea, obesity and, more rarely, diabetes insipidus, hypertricosis, acromegaly and dwarfism. Endocrine abnormalities may constitute the only symptoms of the patients and in many cases they can reverse after treatment of hydrocephalus.

Patterns of evolution

Orderly loss of eye movement: Because of the anatomical relationship of these structures, eye signs appear in a typical order during progression of hydrocephalus (15). Usually upward gaze paralysis manifests before downward and lateral gaze impairment. Pupillary dilation and the paralysis of light reflex tend to occur when hydrocephalus is advanced.

Midbrain dysfunction: Severe hydrocephalus that develops rapidly results in a global dysfunction of the rostral midbrain. While it may also develop in patients first presenting with hydrocephalus, it is much more probable following shunt failure and sudden blockage of CSF drainage in patients with aqueductal stenosis (6, 18). Severe and acute deformation of the midbrain due to the formation of a pressure gradient between the supra and infratentorial compartment can explain the functional impairment of the whole dorsal midbrain during shunt malfunction. In this acute phase, T2-weighted sagittal MRI could show marked hyperintensity in the rostral midbrain, probably secondary to focal edema. These changes are usually rapidly reversible following ETV(18)

Time for evolution

Insidious onset: More often the onset is insidious (112). Acute onset with headache, nausea and vomiting, visual disturbances, seizures, changes in mental state and coma is rare in both children and adults (only 15%) (112).

Sudden deterioration after chronic history of psychomotor retardation: Some patients with a chronic history of symptoms, such as retarded psychomotor development, school difficulties, temporary headache, endocrine disturbances, or growth retardation, may show acute progression of symptoms as the result of further decompensation of the hydrocephalus, sometimes following minor head injury, febrile infections or subarachnoid hemorrhage (31, 37, 87, 112).

Intervention

Stabilization

EVD: Rarely when there is insufficient time to move a patient to the operating room for an emergency ETV an emergency EVD may be needed to normalize the ICP.

Preparation for definitive intervention, nonemergent

Elective ETV when chronic history of symptoms: Symptoms of a more chronic nature such as retarded psychomotor development (school difficulties), sporadic headaches, endocrine disturbances, growth retardation, and/or visual disturbances identify a patient who can be managed nonemergently.

Imaging: Either a CT scan or MRI (3D CISS or DRIVE sequence, and cine-MRI) is obtained in preparation for surgery.

Endocrinological evaluation: If possible laboratory screening for endocrinopathy should be done.

Neuropsychological evaluation: If possible, this can be done to allow documentation of impact of treatment (comparison of pre- and postoperative testing).

Preparation for definitive intervention, emergent

Emergency surgery for acute or subacute symptoms: When there has been acute or subacute development of headache, nausea and vomiting, visual disturbances (sixth nerve palsy, Parinaud’s sign, raised ICP at funduscopic examination), seizures, or changes in mental state and coma, the authors intervene emergently to perform an ETV.

Imaging: Either a CT scan or MRI (DRIVE sequence) is obtained in preparation for surgery.